Reclining chair



Jan. 19, 1965 F. M. RE 3,166,353

RECLINING CHAIR Filed March 26, 1963 3 Sheets-Sheet 1 INVENTOR FRANK M. RE

ATTORNEY.

Jan. 19, 1965 F. M. RE 3,166,353

RECLINING CHAIR Filed March 26, 1963 3 Sheets-Sheet 2 INVENTOR.

FRANK M. RE

ATTORNEY.

Jan. 19, 1965 F. M. RE 3,166,353

RECLINING cum Filed March 26, 1963 3 Sheets-Sheet 3 INVENTOR.

FRANK M. RE

ATTORNEY.

United States Patent Mass.

Filed Mar. 26, 1963, Ser. No. 268,050 3 Claims. (Cl. 29775) The present invention relates to improvements in reclining chairs and particularly to a reclining chair having a novel multi-part, fold-away leg-rest and wherein the seat and back rest and leg-rest are pivotal relative to a fixed base or chassis for coordinated movement via a linkage system relative to said base.

For a better understanding of the invention and its contribution to the development of the art, it is necessary to consider generally the construction and operation of reclining chairs.

There are three basic types of reclining chairs, namely so-called 3-way lounger chairs, so-called 2-way rester chairs, and so-called TV reclining chairs. The 3-way lounger chair has a separately movable seat and backrest such that the seat can incline at a rate different from that of the back-rest which is reclined all while-the legrest is extended. The 2-way rester, chair has a seat and back rigid with each other to form a unitary body-supporting unit. In the lounger chair, there is necessarily a coordinating linkage on the support between the backrest and the seat mounted on the support or frame and arranged to incline the seat under the control of the backrest. In the rester chair, there is no coordinating linkage necessary since the seat and back-rest are unitary, and usually this one-piece body-supporting unit is mounted on the support by a single pivot. The TV type of chair is a multiposition type of chair allowing an upright sitting position and a reclining position and an intermediate position therebetween ideal for television viewing.

The above types of chairs will have a leg-rest which moves into an elevated leg-supporting position in response to the rearward movement of the seat and back-rest. The coordination and control of the leg-rest involves several problems. Initially the leg-rest must be guided to follow a certain route from an inactive position below the front of the seat when the body-supporting means is in the upright sitting position to an extended position forwardly of the seat when the chair is in a TV viewing position. Too, the leg-rest movement must be coordinated with the movement of the seat and back-rest. When the leg-rest unit is of the fold-away, multi-part type, as is true herein, the problem is further complicated by the fact that both parts of the leg-rest unit must be coordinated with the movement of the seat and back-rest.

Corresponding to these problems in coordinating and controlling the leg-rest movement there are several linkage components. The first of these components controls the route the leg-rest follows such that the leg-rest traces a generally rectilinear line pat The components in the chair which establish this leg-rest motion can be designated as a route control means. The second of these components might be designated as a movement control means. This movement control means is distinct from the route control means and is a means to control the rate of movement of the leg-rest along its prescribed rectilinear path. The rate of movement of the leg-rest is very important in a reclining chair because it determines the position of the leg-rest at various positions of the chair. Too, the rate of movement of the leg-rest sets the balance of the chair. If the rate of movement is not uniform, the chair balance will be poor. The last of these components might be designated as a dual movement control means. This component effectuates the EJ6 5553 Patented Jan. 19, 1965 movement of an auxiliary foot rest while the main legrest is being extended.

The modern reclining chair, a relatively recent innovation, may be described as the type which can be moved by the chair occupant without the necessity of external locks and levers and which can be maintained in any of a plurality of intermediate positions. These chairs are self-operating and require no external locking or lever arrangement because of proper chair balance.

It is a primary object of this invention to provide a reclining chair including a multi-part leg-rest interconnected via a linkage mechanism with the stationary and reclining elements thereof for movement between retracted and extended positions, and positions therebetween, with such movementbeing coordinated with the movement of the reclining elements relative to the stationary elements. Further, I provide an improved reclining chair having a multi-part, fold-away leg supporting unitincluding a main leg-rest portion and an auxiliary leg-rest portion, which portions may be moved unitarily between a stored non-operative position beneath the seat and an extended operative position forwardly thereof, when the pivotally interconnected seat and back-rest are tilted, with the auxiliary leg-rest portion being disposed rearwardly of the main leg-rest portion in said stored non-operative position wherefore it is hidden from view during assumption of the normal upright position of the chair, and being positionable in axial alignment with the main leg-rest portion when the chair is moved to one of a plurality of semi-reclined or fully reclined positions.

Another object of the invention is to provide a reclining chair including a seat and back rest movable relative to each other and having a leg-rest control linkage adapted to eiiect a generally rectilinear movement of said seat and of a multi-part, fold-away leg supporting unit, while an auxiliary leg-rest portion thereof describes a generally arcuate path in arriving at its required position of axial alignment with a main leg-rest portion thereof at any one of a multiplicity of reclined positions of the chair from a TV position or intermediate position to a fully reclined position.

The invention contemplates a novel article of furniture having multiple coacting parts which are relatively spaced on and swingable relative to a stationary base whereby the chair components may be actuated by the occupant with facility so as to move same between a normal upright or sitting position and one of a multiplicity of reclining positions. In assuming any reclined position, the seat and the back-rest pivoted thereto are swingable relative to a base to effect angularization of the seat and back-rest relative to the base and simultaneously to bring about the swinging or shifting of the multi-part leg-rest relative to the angularization of the seat and back-rest and further to permit the adjustment of the multi-part leg-rest component independent of the relative positioning of the other components, all in manner, whereby the components are maintained in a balanced relationship at all times wherewith a fluidity of maneuverability of the movable body and leg-supporting members is allowed with a minimum of effort and a maximum of ease.

The characteristic features which I consider to be novel with my invention,

"ice

as to its construction and organization and as to its methods of manufacture and operation, will be better understood from a consideration of the following detailed description forming a part of this specification, when read in conjunction with the illustrations in the accompanying drawings, wherein like characters of reference are employed to designate like or corresponding parts throughout the several views and in which:

FIG. 1 is a fragmentary side elevational View of a reclining chair incorporating a preferred embodiment of the invention, said chair being shown in the upright position;

FIG. 2 is a side elevational view of the linkage mechanism shown in FIG. 1, said mechanism being shown in an intermediate reclining position; and 1 FIG. 3 is a side elevational view of the linkage mechanism shown in FIG. 1, said mechanism being shown in the fully reclined position.

Referring now to the drawings, I have shown in FIG. 1 a reclining chair comprising a stationary supporting framework 10, a seat 12, and a back-rest 14, said'backrest being pivotal relative to said seat and both said back rest and seat being pivotal relative to said supporting framework.

Said seat and back-rest form a body-supporting unit which defines a thoracic support area A, a lumbar support area B, a sacrum support area C, an ischial tuberosity support area D, and a popliteal support area E.

Said body-supporting unit is so balanced relative to supporting framework as to provide for the chair occupant'a back angle of approximately 25 and a hip angle of approximately 96 in upright and intermediate reclining positions of the chair, these angles representing the optimum for the support areas A-E to render maximum comfort and therapeutic effect to the chair occupant.

Too, in the semi-reclining and fully reclining positions of the chair, the knee angle of the occupant will be approximately l28, this also representing the optimum angle for comfort and therapeutic effect.

The mechanism now to be described is one of a pair located one at each side of the chair between supporting framework It) and the seat and back-rest and fixed to a stationary chair brace 16 which extends transversely relative to said supporting framework. Herefollowing, only one such mechanism is shown and described.

"A substantially horizontally-extending base bracket 18 is rigidly fixed to stationary chair brace 16 and to framework 10 by screws 19 and 21 respectively or any other suitable means and extends lengthwise or in a frontrear dimension of the chair. A stop 20 extends out- Wardly from base bracket 18 and serves to limit movement of the linkage mechanismas will appear. A seat bracket 22 is rigidly secured to the lower edge of seat 12 as by screws 24 or the like. A stop 26 extends outwardly from seat bracket 22 adjacent the forward end thereof and serves to limit the movement of the leg-rest unit, as will subsequently appear.

An L,-link 28 fixed to a side of back-rest 14, as by screws 30, includes a lower forwardly extending foot portion 28, the forward face end of which is pivotally connected to seat bracket 22 as by a connection 32.

The back-rest 14 is pivotally supported for movement relative to the supporting framework by means of a primary support link 34 pivotally connected at its upper end, at 36, to foot portion 28' of L link 28 and pivotally connected at its lower end, at 38, to base bracket 18. I The seat 12 is also pivotally supported for movement relative to the supporting framework by means of sec ondary and tertiary support links 40 and 42 respectively.

The seat-back structure is thus pivotally supported for movement relative to the supporting framework by means of the support links 34, 4t} and 42.

A multi-part fold-away leg-rest unit, generally indicated by 50, is positioned at the forward end of the chair and comprises a main leg-rest portion 52 and an auxiliary leg-rest portion 54 pivoted thereto adjacent its lower end. Leg-rest unit 5% is mounted by a control linkage, subsequently to be described, on the forward end of seat 12 for movement between a retracted position, as shown in FIG. 1, and one of a plurality of extended positions,

g, as shown in FIGS. 2-3, and a pluralityof positions therebetween.

In a fully upright position of the chair, as illustrated in FIG. 1, main leg-rest portion 52 is disposed flush with the forward end of the seat, while auxiliary legrest portion 54 extends rearwardly from the lower end of main leg-rest portion 52 and is hidden from view beneath the seat. When main leg-rest portion 52 is elevated and advanced, auxiliary leg-rest portion 54 is moved to a position forwardly thereof and in axial alignment therewith.

Leg-rest unit is suspended from seat 12 by means of a linkage system which includes said tertiary support link 42, same also functioning to actuate primary and secondary elevator links 58 and 60 respectively linked thereto.

Tertiary support link 42 is pivoted at 62 at its upper end to seat 12 and is pivoted at 64 at its opposite or lower end to the lower end of primary elevator link 58.

A secondary propeller link 56 is pivoted at its upper end at 66 to the seat 12, at its approximate midsection at es to the midsection of primary elevator link 58, and at its lower end at 70 to the lower end of secondary elevator link 60.

Secondary elevator link 60 is pivoted at 72 at its op posite or forward end to a main leg-rest link 74 which forms a support for main leg-rest portion 52 and is fixed thereto as by screws 75 or the like. Elevator link 60 is pivoted at 76 at its approximate midsection to the midsection of a first connecting link 78.

A side edge of secondary elevator link 69 will be fiattened as at 77 adjacent the lower end of said link with said flattened portion 77 being receivable in a longitudinally-extending notch 79 provided in the adjacent side edge of primary elevator link 58 in the upright position of the chair. With such an arrangement, any unwanted rearward movement of the leg-rest unit beyond the limits dictated by the upright position of the chair is precluded.

First connecting link 78 is pivoted at 80 at its upper end to the upper end of primary elevator link 58 and is pivoted at 82 'at its opposite or lower end to the lower end of a second connecting link 84.

Second connecting link 84 is pivoted at 85 at its forward end to an auxiliary leg-rest link 88 which forms a support for auxiliary leg-rest portion 54 and is fixed thereto as by screws 89 or the like. Auxiliary leg-rest l7ink 83 is pivotally connected at 9% to main leg-rest link A control link 92 extends between main leg-rest link 74 and second connecting link 84 and is pivoted at 9 3 at one end to main leg-rest link 74 and is pivoted at 95 at its opposite end to second connecting link 84.

V A base link interconnects the aforedescribed leg-rest linkage means to the chair base by means of tertiary support link 42 which is pivoted at 98 to a forward portion of base link 95, which base link 96 rotates about a pivot 1% by means of which it is pivoted, at its rearward portion, to base bracket 18. V

The lower longitudinal edge of base link Q6 is provided adjacent its rearward end with a recessed portion to provide a stop 102, for purposes as will appear, and said lower longitudinal edge is also adapted to abut stop 2i) on base bracket 18 to preclude downward movement of base link 96 beyond the desired limits prescribed by the upright position of the chair.

A friction link 1% is disposed upon base link 96, is fixed at its upper end at 1% to base link as and to base bracket 18, and is fixed at its lower end to base bracket 18 in a frictional relationship. A bolt 106 passes laterally through base bracket 18 and the lower end of friction link 1% and has a wing nut 11% threaded thereon, which nut may be tightened against the planar face of friction link 1% in manner to increase the frictional engagement between base link $6 and base bracket 18. Conversely, by loosening wing nut 108, the frictional engagement between base link 96 and base bracket 18 is decreased, same being a desirable feature whereby persons of lighter weight may adjust the device for easier chair operation, as will appear.

In effect, wing nut 108, in combination with friction link 104 may be described as being an adjustable braking device whereby the force or weight required to move the seat and back to one of a plurality of reclining positions may be varied in accordance with the desires or requirements of the chair occupant.

A pivot link 110 is pivoted at 112, at its approximate midsection, to base bracket 18 and at its lower end at 114 to the lower end of secondary support link 40, said secondary support link 40 being pivoted at 32, at its opposite or upper end, to seat 12 and to toe portion 28'.

Pivot link 110 is pivoted at 116, at its opposite or upper end, to the upper end of a tertiary connecting link 118, which tertiary connecting link 118 is pivoted at 120 at its opposite or lower end to the rearward end face of base link 96.

FIG. 1 of the drawings illustrates the relative positions of the components of the linkage, when the chair is in fully upright position. It will be observed that, when the chair components are in this position, leg-rest unit 50 is retracted, with main leg-rest portion 52 being positioned flush with the forward end of seat 12, and with auxiliary leg-rest portion 54 being disposed rearwardly thereof beneath the seat. In this position, base link 96 is in a generally horizontal position abutting stop 20, and the frictional adjustment means (bolt 106 and wing nut 108) is positioned at the forward end of an arcuate surface 122 provided adjacent stop 102 at the rearward end of the lower longitudinal edge of base link 96.

To reach the intermediate reclining position of FIG. 2, from the upright position of FIG. 1, the chair occupant may bring rearward pressure to bear upon back-rest 14, causing the seat-back structure to become angularized relative to stationary base bracket 18 and chair brace 16, while the relative seat-back angle is maintained, by pivotal movement of primary support link 34 upon pivot points 36 and 38, by a similar pivotal movement of secondary support link 40 upon pivot points 32 and 114, and by a similar pivotal movement of tertiary support link 42 upon pivot points 62 and 98.

As previously stated, primary support link 34 is pivotally connected to L-link 28, which is in turn pivotally connected through toe portion 28' to seat bracket 22, wherefore, as the back-rest is moved, the seat is caused to move therewith by pivoting upon pivot point 32. By such pivotal mounting of the seat and back-seat relative to base bracket 18 by support links 34, 40 and 42, the body supporting unit is movable from the upright or sitting position of FIG. 1 to any one of the positions of FIGS. 2-3 or to any position therebetween.

It should be here noted that toe portion 28' need not be pivoted at 32, but may be pivoted to seat bracket 22 at a point either forwardly of or rearwardly of pivot 32, as desired.

In the course of movement from an upright position to a reclining position with the leg-rest extended, support links 34, 40 and 42, and secondary-propeller link 56 pivot in a clockwise direction (as viewed in FIG. 1) as seat bracket 22 and seat 12 are moved. As tertiary support link 42 rotates, it urges primary elevator link 58 forwardly and upwardly and this, in turn, simultaneously urges secondary propeller link 56 forwardly and upwardly to cause a similar movement of secondary elevator link 60 whereby main leg-rest link 74 and main leg-rest portion 52 approach a generally horizontal position.

Similarly, as primary and secondary elevator links 58 and 60 respectively rotate, they cause first and second connecting links 78 and 84 respectively to move forwardly and outwardly urging auxiliary leg-rest link 88 to pivot at 90 relative to main leg-rest link 74.

A smooth swinging movement of auxiliary leg-rest link 88 is ensured by control link 92 which acts to constrain the forward movement of second connecting link 84 and to bring auxiliary leg-rest link 88 into axial alignment with main leg-rest link 74 wherefore main leg-rest portion 52 and auxiliarly leg-rest portion 54 are also placed in axial alignment to form a unit when the chair is in a semi-reclining position, as illustrated by the linkage mechanism of FIG. 2, or a fully reclining position, as illustrated by the linkage mechanism of FIG. 3.

Referring to FIG. 2, it will be observed that, during the sequence of movements just described, base link 96 has not changed its generally horizontal position relative to base bracket 18 and continues to rest on stop 20, while leg-rest unit 50 is fully extended, with main legrest link 74 and auxiliary leg-rest link 88 now being axially aligned. The forward edge of secondary propeller link 56 now abuts stop 26 on seat bracket 22 wherefore further extension of the leg-rest unit is precluded.

It will also be observed that seat bracket 22, L-link 28, and leg-rest unit 50 are so disposed as to maintain the optimum hip angle of approximately 96, the optimum back angle of approximately 25 and the optimum knee angle of approximately 128, all previously alluded to, wherefore maximum comfort and therapeutic effect are afforded to the chair occupant in the support areas A-E.

It should be here noted that, had he so desired, the chair occupant might have positioned the seat and back at any position of reclination between the positions of FIGS. 1 and 2, with a cocomitant partial extension of legrest unit 50.

To reach the fully reclining position of FIG. 3 from the semi-reclining position shown in FIG. 2, the chair occupant may once again bring additional rearward pressure to bear upon the chair back, whereupon the forward end of base link 96 is urged upwardly by tertiary support link 42 through pivotal connection 98 causing base link 96 to swing at its rearward end on point 100. During this movement, secondary propeller link 56 continues to abut stop 26, precluding any further extension of legrest unit 50.

As base link 96 pivots in a clockwise direction, arcuate surface 122 thereof is caused to ride upwardly relative to bolt 106. When rearward stop 102 of base link 96 engages bolt 106, further angularization of the seat and back-rest is precluded and the chair components have assumed a fully reclining position, as shown in FIG. 3.

It will be observed that, as base link 96 swings upon its pivot 100, it etfectuates the forward movement of the upper end of tertiary connecting link 118 and, through the pivotal connection 116 with pivot link 110, causing pivot link to swing upon point 112, thus rotating secondary support link 40 to move seat bracket 22 rearwardly and upwardly to the desired reclining position.

This rearward and upward movement of the seat brings about the rearward and upward movement of toe portion 28 of L-link 28, it being recalled that the toe portion is connected to the seat at 32, whereupon the desired position of reclination of the back-rest is obtained.

The occupant may return the chair from this fully reclining position of FIG. 3 to the semi-reclining position of FIG. 2 by exerting a slight downward pressure upon seat 12, causing arcuate surface 122 of base link 96 to ride downwardly relative to bolt 106 until base link 96 contacts stop 20, while leg-rest unit 50 is maintained in a substantially extended position; or he may return directly to the fully upright position of FIG. 1 by exerting a slight downward pressure of the heels upon leg-rest unit 50 as he continues to exert a downward pressure upon seat 12.

Also, to shift from the fully reclined posit-ion to the inter-mediate or TV position, it is necessary for the chair occupant only to pivot upon his hips so as to lessen his pressure upon the chair back wherefore the chair automatically shifts to the said intermediate or TV position.

In the structure illustrated, control link 92 serves the function of imparting a rotative movement to auxiliary leg-rest link 88 and to auxiliary leg-rest portion 54 to bring it into leg-supporting position, and to maintain it in that position, as desired, when the other chair components are moved.

portion 52 when the chair is moved from a reclining position to a fully upright position.

In essence, by reason of the novel linkage system hereof, auxiliary leg-rest portion 54 may be said to describe an arc in its movements relative to main leg-rest portion 52;, while the other links of the system are describing a generally rectilinear path.

Too, by mean-s of the novel connection between base link 96, pivot link 1110, and secondary support link 40, the

reclining movements of the seat and back-rest are perfectly coordinated.

It is believed that the gist of the invention will be clearly understood from theforegoing disclosure and accordingly, further analysis thereof at this point is con sidered unnecessary, as I have, in accordance with the provisions of the patent statutes, described the construction and principle of operation of my invention together with the apparatus which I believe to represent the best embodiments thereof, to the end that others can, by applying current knowledge, readily adapt it for various applications without omitting features which, from the standpoint of prior art, fairly consitute essential characteristics of its generic and/or specific aspects. The substitution of equivalents and other changes, modifications and alterations as circumstances may suggest or render expedient, are reasonably contemplated, the invention being susceptible of such without departing from its real spirit or underlying principles.

The protection which is sought for this invention-is covered by the language of the above specification and the spirit represented thereby.

The claims are desired to include Within the scope thereof all of said suitable variations, modifications and equivalentsby which substantially the results of the invention may be obtained through the use of substantially the same or equivalent devices or means. Accordingly, limitations hereof should only be made as determined by a proper interpretation of the prior art and the scope of the subjoined claims, in which it is my intention to claim all novelty herein as broadly as possible.

I therefore particularly point out and distinctly claim as my invention:

1. A reclining article of furniture comprising, a stationary frame, a body-supporting unit including a seat portion and a back-rest portion pivotal relative thereto and pivotal each relative to the other, means comprising a trio of support links mounting said body-supporting unit to said stationary frame for movement successively between a sitting position and an intermediate resting position and a fully reclined position and positions therebetween, a multi-part fold-away leg-rest unit including a main leg-rest portion and an auxiliary leg-rest portion pivoted thereto, a. system of linkage for moving said legrest unit between a stored position beneath the seat portion and a position forwardly of the seat portion and "including: a primary elevator link pivoted to one of said support links, a secondary propeller link pivoted to said seat portion and to said primary elevator link, a secondary elevator link pivoted to said secondary propeller link and to said main leg-rest portion, a first connecting link pivoted to said primary and secondary elevator links, a second connecting link pivoted to said first connecting link and to said auxiliary leg-rest portion, a control link pivoted to said main leg-rest port-ion and to said second connecting link whereby said auxiliary leg-rest portion describes an arcuate path relative to said main leg-rest portion while the latter describes a rectilinear path when when said body-supporting unit is moved, a base link pivoted to said one of said support links and to said stationary frame, a pivot link pivoted to said stationary frame and to another of said support links, and a tertiary connecting link pivoted to said base link and to said pivot link whereby generally rectilinear movement of said seat portion imparts a generally swining movement to said back-rest portion assuring the maintenance of the desired angular relationship between said seat portion and said back-rest portion in all positions of said body-supporting unit.

2. In a reclining chair as set forth in claim 1 including,

stop means on the seat portion of said body-supporting unit and stop means on said stationary frame limiting the range of movement of said system of linkage.

3. In a reclining chair as set forth in claim 1 including, means for varying the frictional engagement between said base link and said stationary frame.

References Cited by the Examiner UNITED STATES PATENTS FRANK B. SHERRY, Primary Examiner. 

1. A RECLINING ARTICLE OF FURNITURE COMPRISING, A STATIONARY FRAME, A BODY-SUPPORTING UNIT INCLUDING A SEAT PORTION AND A BACK-REST PORTION PIVOTAL RELATIVE THERETO AND PIVOTAL EACH RELATIVE TO THE OTHER, MEANS COMPRISING A TRIO OF SUPPORT LINKS MOUNTING SAID BODY-SUPPORTING UNIT TO SAID STATIONARY FRAME FOR MOVEMENT SUCCESSIVELY BETWEEN A SITTING POSITION AND AN INTERMEDIATE RESTING POSITION AND A FULLY RECLINED POSITION AND POSITIONS THEREBETWEEN, A MULTI-PART FOLD-AWAY LEG-REST UNIT INCLUDING A MAIN LEG-REST PORTION AND AN AUXILIARY LEG-REST PORTION PIVOTED THERETO, A SYSTEM OF LINKAGE FOR MOVING SAID LEGREST UNIT BETWEEN A STORED POSITION BENEATH THE SEAT PORTION AND A POSITION FORWARDLY OF THE SEAT PORTION AND INCLUDING: A PRIMARY ELEVATOR LINK PIVOTED TO ONE OF SAID SUPPORT LINKS, A SECONDARY PROPELLER LINK PIVOTED TO SAID SEAT PORTION AND TO SAID PRIMARY ELEVATOR LINK, A SECONDARY ELEVATOR LINK PIVOTED TO SAID SECONDARY PROPELLER LINK AND TO SAID MAIN LEG-REST PORTION, A FIRST CONNECTING LINK PIVOTED TO SAID PRIMARY AND SECONDARY ELEVATOR LINKS, A SECOND CONNECTING LINK PIVOTED TO SAID FIRST CONNECTING LINK AND TO SAID AUXILIARY LEG-REST PORTION, A CONTROL LINK PIVOTED TO SAID MAIN LEG-REST PORTION AND TO SAID SECOND CONNECTING LINK WHEREBY SAID AUXILIARY LEG-REST PORTION DESCRIBES AN ARCUATE PATH RELATIVE TO SAID MAIN LEG-REST PORTION WHILE THE LATTER DESCRIBES A RECTILINEAR PATH WHEN WHEN SAID BODY-SUPPORTING UNIT IS MOVED, A BASE LINK PIVOTED TO SAID ONE OF SAID SUPPORT LINKS AND TO SAID STATIONARY FRAME, A PIVOT LINK PIVOTED TO SAID STATIONARY FRAME AND TO ANOTHER OF SAID SUPPORT LINKS, AND A TERTIARY CONNECTING LINK PIVOTED TO SAID BASE LINK AND TO SAID PIVOT LINK WHEREBY GENERALLY RECTILINEAR MOVEMENT OF SAID SEAT PORTION IMPARTS A GENERALLY SWINGING MOVEMENT TO SAID BACK-REST PORTION ASSURING THE MAINTENANCE OF THE DESIRED ANGULAR RELATIONSHIP BETWEEN SAID SEAT PORTION AND SAID BACK-REST PORTION IN ALL POSITIONS OF SAID BODY-SUPPORTING UNIT. 